Poor Fuel Economy
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Suggest to the driver to read the Important Facts on Fuel Economy in the Owner Manual.
- Confirm proper interpretation of the Average Fuel Economy value on the DIC. The Fuel Economy value should be reset periodically. Particularly if driving patterns, including load, terrain, etc., have changed significantly since the last Fuel Economy Reset.
- Suggest to the owner to fill the fuel tank and inspect the fuel economy.
- The following conditions can reduce fuel economy:
- Aftermarket body accessories that can affect wind flow over the vehicle. Including air deflectors, flares, etc.
- Heavy loads being carried or towed, or the shape of large loads
- Extended idle time
- Acceleration rate too much or too often
- Incorrect tire size or air pressure
- Improper fuel quality and rating-Refer to Contaminants-in-Fuel Diagnosis and Fuel System Specifications .
- Aftermarket ECM calibrations
- Certain aftermarket air filters or air induction systems
- An air leak in the induction or engine systems-Refer to full system air leak test in Charge Air Cooler Diagnosis (Induction System Smoke Test) or Charge Air Cooler Diagnosis (Full System Air Leak Test) or Charge Air Cooler Diagnosis (Charge Air Cooler Air Leak Test) .
- Fuel system issues-Inspect the injector balance rates. Balance rates should be between +4 mm3 and -6.9 mm3 in Park or Neutral.
- Brake system drag
- Air conditioning system improper operation
- Incorrect operation of the speedometer